The automotive industry is currently under a lot of scrutiny when considering the materials used in a vehicle and the efficiency of a vehicle. The weight of a vehicle can have an impact on its efficiency. Therefore if new products can be developed that reduce the weight of a vehicle this provide an advantage during the manufacturing of the vehicle when those parts are shipped and it also reduces the cost to operate the vehicle.
Leaf springs perform an important function in a vehicle, particular in regard to driving comfort. Specifically, leaf springs function in whole or in part to hold the chassis at ride height; controls the rate at which the chassis rolls; controls the rear end wrap up; controls axle dampening; controls lateral forces such as side load, pan hard, or side bite; controls brake dampening forces; and sets wheel base lengths during acceleration and deceleration.
Steel leaf springs used in vehicles are typically a plurality of stacked steel leaf springs to create a spring pack. The spring packs are hung from the frame rail by shackles (hangers), which allow the springs to flatten out during weight increase or load; the shackles would move or pivot, allowing them to absorb the weight increase. The closer the shackle is to a vertical angle, the higher the effective spring rate. When the shackle is laid back at an angle, it actually becomes a moving link with the spring, and the spring ride will feel softer.
There are a number of limitations to the steel leaf spring packs. For example, during static load, spring leaf packs have friction between the leaves, causing the springs to ride rough over small bumps because the spring must overcome the pack friction before it starts to flex. For example, rolling slowly over a speed bump, at the bottom of the speed bump, the suspension is rigid with no active suspension absorbing any of the impact.
Further disadvantages include the weight, which contributes to poor fuel economy; steel leaf springs have a lower impact strength than composites which attributes to leaf spring failure; steel leaf springs are pre-bent and will naturally loose their arch height causing the vehicles ride height to change; steel leaf springs corrode over time and can cause premature failure of the spring; and steel leaf springs have a lower fatigue life then composite leaf springs.
Accordingly it would be advantageous to provide a leaf spring that is lighter than the comparable steel spring currently being used in many vehicles. Further, it would be advantageous to provide a composite leaf spring.